viii PREFACE TO THE SECOND EDITION
example, in submitting specimens of new or rare preparations, or
in presenting an account of some small investigation.
The present edition is much enlarged and contains new pre-
parations, reactions and quantitative methods, all of which have
been carefully revised. My object has been not to follow any
particular syllabus, but to present a variety of processes from
which a selection "may be made to suit the special needs of
My thanks are due to Mr. Joseph Marshall, B.Sc., and
several of my senior students, for their assistance in the work of
J. B. COHEN
THE UNIVERSITY, LEEDS.